From patchwork Fri Mar 15 19:51:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 10855513 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 30CBC15AC for ; Fri, 15 Mar 2019 19:52:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1ABF92AC54 for ; Fri, 15 Mar 2019 19:52:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0D4BF2AC57; Fri, 15 Mar 2019 19:52:29 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE, USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8B7582AC54 for ; Fri, 15 Mar 2019 19:52:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 71E546B02BF; Fri, 15 Mar 2019 15:52:26 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 6CDD16B02C0; Fri, 15 Mar 2019 15:52:26 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5E5606B02C1; Fri, 15 Mar 2019 15:52:26 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from mail-yw1-f71.google.com (mail-yw1-f71.google.com [209.85.161.71]) by kanga.kvack.org (Postfix) with ESMTP id 386B36B02BF for ; Fri, 15 Mar 2019 15:52:26 -0400 (EDT) Received: by mail-yw1-f71.google.com with SMTP id v123so13111721ywf.16 for ; Fri, 15 Mar 2019 12:52:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=sAfWvHiPwt89rwowuJd122MWpb2hIcncHtjST15rjKY=; b=NbtB3T0/3t97vdrygB89AoZUjRj2MQ4tWNwtpMTVBXY7kvmWlybCvYfIz7QOwIktbT z9D5CyJZVg2pqLQr3WDE49WO18dRyp1AIizRyu6TG8/2ZNkYgGWMXVfvbjRLWCyubweR fYHp/yxWGpmI5xIWBPy7kS2e3Xnu5NtxttXqFWdIL42taMe7EjnINyNUdtGJwW5q7RbX 8BHM/KoS3/eGXn/weFi4NqKyQ0ldqMXKUxZw3V/H1P21pbK76px6l6UwqptFen1KzBJ2 VFMBJxVaiga6WQqyBuAPT1XoSX/BeDmSI9FRD9b15W5DGUnq9G/vJrmRumKioSIMe4GZ EPCQ== X-Gm-Message-State: APjAAAXZYnoFucE6ZKhJojXn9o/QAkuCrcUs6LgCQoHuhQozBwQqi+ir 4zlldcX7OLq/uQ0gHUl+OsG6VGWSq+zkVpbjOBWYxe4MP8fcEc2dyJwMdqVyG6BS8C+Bt2k6wtH zXI3IGF7VOR536Aa2QT9Ts7/cBqHpx4m43mI5vTh4mg18qpGM+sSaP94Ww2Pm3qqyFA== X-Received: by 2002:a25:7582:: with SMTP id q124mr4788920ybc.136.1552679546008; Fri, 15 Mar 2019 12:52:26 -0700 (PDT) X-Received: by 2002:a25:7582:: with SMTP id q124mr4788874ybc.136.1552679545187; Fri, 15 Mar 2019 12:52:25 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1552679545; cv=none; d=google.com; s=arc-20160816; b=CvEa13fq/69vsoapHo3gl6Zr+VjmFx3ndJupJdSIGfrw4QBF0eb7MjSwAhdA3k8Sfc 9achUukg6w/1HQEtU0kqxgcUNmeFeq32qvhcdZHXp0wva7CE6gn9Nua4HJ1mTTXOVRvV SCQCRDGM2xMvADdNojXqLZzuE98D6aGPziH58rrYHEKds465rMUx1OrOVlpsRhxlEwHY dyAha3cVkvxfbABR6pDJRXfcNAaCdMT+m+3vUDA+4pb0/ILb2lo6i0srx8XKbvjCEFky VD/M4pkIBzv2yoOR++EVdLBB88bYKm5vVNfWnB534++sshraOX81TNVGAIGI+a4nI8rH t1ng== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:dkim-signature; bh=sAfWvHiPwt89rwowuJd122MWpb2hIcncHtjST15rjKY=; b=yS/GyqZO8gOQatx4GMXq39w6K7Av4MlZ85DXhHPGCB46IA6AcYsmEFT1C3TZtVsf8F kEZvKp7CkbdJbw3U2212dQFvF9utOEuIk427oEmau6gCsObeDgAe35p+szSHCjErHdE9 Q7ft7wIt+k5krYKul8pyX3nSGcEj7v4HKHsv0NeUe+d8UQMnhXcyu5a9meVSF97YLh/t 3e1+QkZHAog95bDl9EWCRi7N9+XZZnV+lQcNZp885jL/jn/dzVg5JMOWOPv3L85/t0y5 i7ey+FiXHHudvt58jD50DknYvmBURk+9ChCZtahM3KEkli+XPA40o05LTiVcEnsUcYnK V/Wg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=m8TjLlxT; spf=pass (google.com: domain of 3eakmxaokcjc1e4i5pbemc7ff7c5.3fdc9elo-ddbm13b.fi7@flex--andreyknvl.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3eAKMXAoKCJc1E4I5PBEMC7FF7C5.3FDC9ELO-DDBM13B.FI7@flex--andreyknvl.bounces.google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from mail-sor-f73.google.com (mail-sor-f73.google.com. [209.85.220.73]) by mx.google.com with SMTPS id i9sor1679568yba.142.2019.03.15.12.52.25 for (Google Transport Security); Fri, 15 Mar 2019 12:52:25 -0700 (PDT) Received-SPF: pass (google.com: domain of 3eakmxaokcjc1e4i5pbemc7ff7c5.3fdc9elo-ddbm13b.fi7@flex--andreyknvl.bounces.google.com designates 209.85.220.73 as permitted sender) client-ip=209.85.220.73; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=m8TjLlxT; spf=pass (google.com: domain of 3eakmxaokcjc1e4i5pbemc7ff7c5.3fdc9elo-ddbm13b.fi7@flex--andreyknvl.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3eAKMXAoKCJc1E4I5PBEMC7FF7C5.3FDC9ELO-DDBM13B.FI7@flex--andreyknvl.bounces.google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=sAfWvHiPwt89rwowuJd122MWpb2hIcncHtjST15rjKY=; b=m8TjLlxTJg+rOoEWUReYdn8rdh11EMoghrFHbVAb9WAMjVa0U/T9FqdGOvqwTZpUfm vVbcFLqWrP3TVwdj34DrYszJNIoQ9EJXeAXrC/wvs/z5IYKQAqYP9RwBD+8emDJu5PVP Vo+huuqc6PHspT4+rXUR6NPieF9KLiWfhrJ7gi13d3MatbDKM4RF0bkO2DrrarQnmyYR 3h3NjRcSXCNOJ75ka4ui6zatbnk/g1PfEFqJlZRnqOTJFOnY1jqqoDx3fG9sQrGexBtX ZZ96/DuknTpKXEYqtVY62yQBCWP1T+ifr5PT3FJRXj7RVMG+M4Fgps93zJ4tkNbNYwin RjCQ== X-Google-Smtp-Source: APXvYqx6fJ/Xf2Wycfnq24ZgFIr73HZ4gPKerA6ul2fF+VVXr0NweKm2RI8g9OR3XNR3hwcUmUxVL0qXK1MAydWo X-Received: by 2002:a25:41c2:: with SMTP id o185mr2528725yba.96.1552679544923; Fri, 15 Mar 2019 12:52:24 -0700 (PDT) Date: Fri, 15 Mar 2019 20:51:37 +0100 In-Reply-To: Message-Id: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.21.0.360.g471c308f928-goog Subject: [PATCH v11 13/14] arm64: update Documentation/arm64/tagged-pointers.txt From: Andrey Konovalov To: Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , Vincenzo Frascino , Eric Dumazet , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy , Andrey Konovalov X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP This patch is a part of a series that extends arm64 kernel ABI to allow to pass tagged user pointers (with the top byte set to something else other than 0x00) as syscall arguments. Document the ABI changes in Documentation/arm64/tagged-pointers.txt. Signed-off-by: Andrey Konovalov --- Documentation/arm64/tagged-pointers.txt | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/Documentation/arm64/tagged-pointers.txt b/Documentation/arm64/tagged-pointers.txt index a25a99e82bb1..07fdddeacad0 100644 --- a/Documentation/arm64/tagged-pointers.txt +++ b/Documentation/arm64/tagged-pointers.txt @@ -17,13 +17,15 @@ this byte for application use. Passing tagged addresses to the kernel -------------------------------------- -All interpretation of userspace memory addresses by the kernel assumes -an address tag of 0x00. +The kernel supports tags in pointer arguments (including pointers in +structures) of syscalls, however such pointers must point to memory ranges +obtained by anonymous mmap() or brk(). -This includes, but is not limited to, addresses found in: +The kernel supports tags in user fault addresses. However the fault_address +field in the sigcontext struct will contain an untagged address. - - pointer arguments to system calls, including pointers in structures - passed to system calls, +All other interpretations of userspace memory addresses by the kernel +assume an address tag of 0x00, in particular: - the stack pointer (sp), e.g. when interpreting it to deliver a signal, @@ -33,11 +35,7 @@ This includes, but is not limited to, addresses found in: Using non-zero address tags in any of these locations may result in an error code being returned, a (fatal) signal being raised, or other modes -of failure. - -For these reasons, passing non-zero address tags to the kernel via -system calls is forbidden, and using a non-zero address tag for sp is -strongly discouraged. +of failure. Using a non-zero address tag for sp is strongly discouraged. Programs maintaining a frame pointer and frame records that use non-zero address tags may suffer impaired or inaccurate debug and profiling